Perl is my first programming language. I wrote this to play with pattern matching and filehandles. Please could someone explain why this code does everything I ask except print to the screen a count of the number of instances of the word I'm substituting? Massive thanks. 
#! c:\perl\bin

print("Enter filename to open (text only):\n\n");
$in=<STDIN>;
chomp $in;
    if ($in !~ /\.txt$/i)
        {
            $in.=".txt";
        }
open ($in, "$in") or die("$in could not be opened:$!\n");    

print("Enter string to replace \"and\" with:\n\n");
$word=<STDIN>;
chomp $word;

print("Enter filename to SAVE text file as:\n\n");
$out=<STDIN>;
chomp $out;
    if ($out !~ /\.txt$/i)
        {
            $out.=".txt";
        }


open($out, ">$out") or die $!;

print ("\n\n\n");

$count=0;

while (<$in>)
        {            
        s/\band\b/$word/ig;
                
                while (/\band\b/ig)
                    {
                    ++$count;
                    }
                    
        print($out "$_\n");
}

print "there were $count instances of \"and\" in $in";
close $out;
close $in;

[download]
UPDATE. Thanks everyone! Most helpful.

In reply to Counting instances of words by scarymonster

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